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The cochlea has what type of organization?

Tonotopic organization


The Organ of Corti is located in which part of the cochlea?

Scala Media (Cochlear duct)


What type of sensory innervation does the Scala media have?

Special somatic afferent innervation


Inner hair cells have what type of innervation?

Primarily afferent innervation but some efferent to the Spiral ganglion.


Outer hair cells have what type of innervation?

Primarily efferent innervation with some afferent, controlling the tectorial membrane.


In the ascending auditory system, the only part of this pathway that is unilateral and that's not binaural?

Cochlear nucleus


After you get past the cochlear nucleus, what changes in the auditory pathway?

Things become bilateral


If you damage the cochlear nucleus, what can happen?

unilateral, sensorineural deafness


If you damage anything past the cochlear nucleus, what can happen?

There is so much crossover, you will still have bilateral hearing


What are the two major parts the cochlear nucleus is broken up into?

1. Anterior cochlear nucleus (ACN)

2. Posterior cochlear nucleus (PCN)


What is the anterior cochlear nucleus (ACN) broken up into? (2)

1. Ventral posterior cochlear nucleus

2. Ventral anterior cochlear nucleus


What is special about the anterior portion of the anterior cochlear nucleus (ACN)?

It is tonotopically oriented


The spiral ganglion is located where and what type of neurons are they associated with?

1. Located in the cochlea

2. Location of first-order neurons


Bipolar neurons run from what types of cells to the spiral ganglion? Where do they go after?

Bipolar neurons that run from inner hairs and outer hair cells to spiral ganglion. After the spiral ganglion, they run to the cochlear nucleus


What are the 3 areas of the cochlear nucleus that the spiral ganglion project to?

1. anterior cochlear nucleus (AVCN - anterior ventral cochlear nucleus)

2. dorsal (posterior) cochlear nucleus (DCN)

3. posterior (portion of the) anterior cochlear nucleus (VPCN - ventral posterior cochlear nucleus)


What cell types make up the Dorsal Cochlear Nucleus (DCN)? (2)

  1. Pyramidal cells
  2. stellate cells




The Dorsal Cochlear Nucleus (DCN) send projections via what?

They send afferent projections to the higher portions of the brainstem (pons) via the Dorsal Acoustic Stria (DAS)


The Ventral Posterior Cochlear Nucleus (VPCN) send projections up to the upper portion of the pons via what?

Intermediate Acoustic Stria (IAS)


What cell types make up the Anterior Ventral Cochlear Nucleus (AVCN)? (2)

1. Stellate cells

2. Bushy cells


What is the primary projecting pathway in the auditory pathway that projects to the third order neurons?

Ventral acoustic stria (trapezoid body)  from the Anterior Ventral Cochlear Nucleus (AVCN) 


How does the Anterior Ventral Cochlear Nucleus (AVCN) project to third-order neurons?

Ventral Acoustic Stria aka Trapezoid Body


What is the first nucleus that is projected to from the cochlear nucleus?

Superior olivary nucleus


 What does the Superior olivary nucleus project up to?

  • Nucleus lateral lemniscus
  • Inferior colliculus


What does the Ventral Acoustic Striae (Trapezoid Body) project to in the midbrain?

Inferior colliculus


The dorsal acoustic striae (DAS) will bypass what and also go to the inferior colliculus?

The lateral lemniscus nucleus


What is a housing point (nuclei) for neurons in the midbrain?

Nucleus lateral lemniscus


What is the tract of ascending neurons that synapse at the inferior colliculus of the midbrain?

Lateral lemniscus


If a tract does not synpase in nucleus lateral lemniscus before ascending to the inferior colliculus, what do you not have?

It does not become a fourth-order neuron. It stays whatever type of neuron it was prior to projecting out.


Where are first-order neurons in the auditory tract?

At the spiral ganglion in the cochlea


Where are second-order neurons in the auditory tract?

Cochlear nucleus in the medulla